add: extension env-injector

schema/snapcraft.json

@@ -906,6 +906,7 @@
                             "uniqueItems": true,
                             "items": {
                                 "enum": [
+                                    "env-injector",
                                     "flutter-stable",
                                     "flutter-beta",
                                     "flutter-dev",

snapcraft/extensions/_ros2_humble_meta.py

@@ -64,8 +64,8 @@ def get_root_snippet(self) -> Dict[str, Any]:
         return root_snippet
 
     @overrides
-    def get_app_snippet(self) -> Dict[str, Any]:
-        app_snippet = super().get_app_snippet()
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
+        app_snippet = super().get_app_snippet(app_name=app_name)
         python_paths = app_snippet["environment"]["PYTHONPATH"]
         new_python_paths = [
             f"$SNAP/opt/ros/underlay_ws/opt/ros/{self.ROS_DISTRO}/lib/python3.10/site-packages",

snapcraft/extensions/_ros2_jazzy_meta.py

@@ -64,8 +64,8 @@ def get_root_snippet(self) -> Dict[str, Any]:
         return root_snippet
 
     @overrides
-    def get_app_snippet(self) -> Dict[str, Any]:
-        app_snippet = super().get_app_snippet()
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
+        app_snippet = super().get_app_snippet(app_name=app_name)
         python_paths = app_snippet["environment"]["PYTHONPATH"]
         new_python_paths = [
             f"$SNAP/opt/ros/underlay_ws/opt/ros/{self.ROS_DISTRO}/lib/python3.12/site-packages",

snapcraft/extensions/_utils.py

@@ -79,8 +79,8 @@ def _apply_extension(
         )
 
     # Apply the app-specific components of the extension (if any)
-    app_extension = extension.get_app_snippet()
     for app_name in app_names:
+        app_extension = extension.get_app_snippet(app_name=app_name)
         app_definition = yaml_data["apps"][app_name]
         for property_name, property_value in app_extension.items():
             app_definition[property_name] = _apply_extension_property(

snapcraft/extensions/env_injector.py

@@ -0,0 +1,125 @@
+# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
+#
+# Copyright 2024 Canonical Ltd.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 3 as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Extension to automatically set environment variables on snaps."""
+
+from typing import Any, Dict, Optional, Tuple
+
+from overrides import overrides
+
+from .extension import Extension
+
+
+class EnvInjector(Extension):
+    """Extension to automatically set environment variables on snaps.
+
+    This extension allows you to transform snap options into environment
+    variables
+
+    It configures your application to run a command-chain that transforms the
+    snap options into environment variables automatically.
+
+    - To set global environment variables for all applications **inside** the snap:
+
+    .. code-block:: shell
+        sudo snap set <snap-name> env.<key>=<value>
+
+    - To set environment variables for a specific application **inside** the snap:
+
+    .. code-block:: shell
+        sudo snap set <snap-name> apps.<app-name>.env.<key>=<value>
+
+    - To set environment file inside the snap:
+
+    .. code-block:: shell
+        sudo snap set <snap-name> env-file=<path-to-env-file>
+    - To set environment file for a specific app:
+
+    .. code-block:: shell
+        sudo snap set <snap-name> apps.<app-name>.envfile=<path-to-env-file>
+
+    """
+
+    @staticmethod
+    @overrides
+    def get_supported_bases() -> Tuple[str, ...]:
+        return ("core24",)
+
+    @staticmethod
+    @overrides
+    def get_supported_confinement() -> Tuple[str, ...]:
+        return ("strict", "devmode", "classic")
+
+    @staticmethod
+    @overrides
+    def is_experimental(base: Optional[str]) -> bool:
+        return True
+
+    @overrides
+    def get_root_snippet(self) -> Dict[str, Any]:
+        return {}
+
+    @overrides
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
+        """Return the app snippet to apply."""
+        return {
+            "command-chain": ["bin/command-chain/env-exporter"],
+            "environment": {
+                "env_alias": f"{app_name}",
+            },
+        }
+
+    @overrides
+    def get_part_snippet(self, *, plugin_name: str) -> Dict[str, Any]:
+        return {}
+
+    @overrides
+    def get_parts_snippet(self) -> Dict[str, Any]:
+        toolchain = self.get_toolchain(self.arch)
+        if toolchain is None:
+            raise ValueError(
+                f"Unsupported architecture for env-injector extension: {self.arch}"
+            )
+
+        return {
+            "env-injector/env-injector": {
+                "source": "https://github.com/canonical/snappy-env.git",
+                "source-tag": "v1.0.0-beta",
+                "plugin": "nil",
+                "build-snaps": ["rustup"],
+                "override-build": f"""
+                rustup default stable
+                rustup target add {toolchain}
+
+                cargo build --target {toolchain} --release
+                mkdir -p $SNAPCRAFT_PART_INSTALL/bin/command-chain
+
+                cp target/{toolchain}/release/env-exporter $SNAPCRAFT_PART_INSTALL/bin/command-chain
+                """,
+            }
+        }
+
+    def get_toolchain(self, arch: str):
+        """Get the Rust toolchain for the current architecture."""
+        toolchain = {
+            "amd64": "x86_64-unknown-linux-gnu",
+            "arm64": "aarch64-unknown-linux-gnu",
+            # 'armhf': 'armv8-unknown-linux-gnueabihf', # Tier 2 toolchain
+            # 'riscv64': 'riscv64gc-unknown-linux-gnu', # Tier 2 toolchain
+            # 'ppc64el': 'powerpc64-unknown-linux-gnu', # Tier 2 toolchain
+            # 's390x': 's390x-unknown-linux-gnu', # Tier 2 toolchain
+        }
+        return toolchain.get(arch)

snapcraft/extensions/extension.py

@@ -66,8 +66,11 @@ def get_root_snippet(self) -> Dict[str, Any]:
         """Return the root snippet to apply."""
 
     @abc.abstractmethod
-    def get_app_snippet(self) -> Dict[str, Any]:
-        """Return the app snippet to apply."""
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
+        """Return the app snippet to apply.
+
+        :param app_name: the name of the app where the snippet will be applied
+        """
 
     @abc.abstractmethod
     def get_part_snippet(self, *, plugin_name: str) -> Dict[str, Any]:

snapcraft/extensions/gnome.py

@@ -85,7 +85,7 @@ def is_experimental(base: Optional[str]) -> bool:
         return False
 
     @overrides
-    def get_app_snippet(self) -> Dict[str, Any]:
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
         command_chain = ["snap/command-chain/desktop-launch"]
         if self.yaml_data["base"] == "core24":
             command_chain.insert(0, "snap/command-chain/gpu-2404-wrapper")

snapcraft/extensions/kde_neon.py

@@ -89,7 +89,7 @@ def is_experimental(base: Optional[str]) -> bool:
         return False
 
     @overrides
-    def get_app_snippet(self) -> Dict[str, Any]:
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
         return {
             "command-chain": ["snap/command-chain/desktop-launch"],
             "plugs": ["desktop", "desktop-legacy", "opengl", "wayland", "x11"],

snapcraft/extensions/kde_neon_6.py

@@ -86,7 +86,7 @@ def is_experimental(base: Optional[str]) -> bool:
         return False
 
     @overrides
-    def get_app_snippet(self) -> Dict[str, Any]:
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
         return {
             "command-chain": ["snap/command-chain/desktop-launch6"],
             "plugs": [

snapcraft/extensions/registry.py

@@ -20,6 +20,7 @@
 
 from snapcraft import errors
 
+from .env_injector import EnvInjector
 from .gnome import GNOME
 from .kde_neon import KDENeon
 from .kde_neon_6 import KDENeon6
@@ -38,6 +39,7 @@
     ExtensionType = Type[Extension]
 
 _EXTENSIONS: Dict[str, "ExtensionType"] = {
+    "env-injector": EnvInjector,
     "gnome": GNOME,
     "ros2-humble": ROS2HumbleExtension,
     "ros2-humble-ros-core": ROS2HumbleRosCoreExtension,

snapcraft/extensions/ros2_humble.py

@@ -87,7 +87,7 @@ def get_root_snippet(self) -> Dict[str, Any]:
         }
 
     @overrides
-    def get_app_snippet(self) -> Dict[str, Any]:
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
         python_paths = [
             f"$SNAP/opt/ros/{self.ROS_DISTRO}/lib/python3.10/site-packages",
             "$SNAP/usr/lib/python3/dist-packages",

snapcraft/extensions/ros2_jazzy.py

@@ -85,7 +85,7 @@ def get_root_snippet(self) -> Dict[str, Any]:
         }
 
     @overrides
-    def get_app_snippet(self) -> Dict[str, Any]:
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
         python_paths = [
             f"$SNAP/opt/ros/{self.ROS_DISTRO}/lib/python3.12/site-packages",
             "$SNAP/usr/lib/python3/dist-packages",

tests/spread/extensions/env-injector/task.yaml

@@ -0,0 +1,127 @@
+summary: Build and run a basic hello-world snap using extensions
+
+systems:
+  - ubuntu-24.04*
+
+environment:
+
+  SNAPCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS: "1"
+  SNAP_DIR: ../snaps/env-injector-hello
+  SNAP: env-injector-hello
+
+prepare: |
+
+  #shellcheck source=tests/spread/tools/snapcraft-yaml.sh
+  . "$TOOLS_DIR/snapcraft-yaml.sh"
+  set_base "$SNAP_DIR/snap/snapcraft.yaml"
+
+restore: |
+
+  cd "$SNAP_DIR"
+  snapcraft clean
+  rm -f /var/snap/"${SNAP}"/common/*.env
+  rm -f ./*.snap
+  rm -rf ./squashfs-root
+  #shellcheck source=tests/spread/tools/snapcraft-yaml.sh
+  . "$TOOLS_DIR/snapcraft-yaml.sh"
+  restore_yaml "snap/snapcraft.yaml"
+
+execute: |
+
+  assert_env() {
+    local snap_app="$1"
+    local env_name="$2"
+    local exp_value="$3"
+
+    local actual_value
+
+    if ! eval "$snap_app" | grep -q "^${env_name}="; then
+      echo "Environment variable '$env_name' is not set."
+      return 1
+    fi
+
+    if [ -z "$env_name" ]; then
+      empty=$( "$snap_app" | grep "=${exp_value}")
+      [ -z "$empty" ] || return 1
+    fi
+
+    actual_value=$( "$snap_app" | grep "^${env_name}=" | cut -d'=' -f2-)
+
+    if [ "$actual_value" != "$exp_value" ]; then
+      echo "Environment variable '$env_name' does not match the expected value."
+      echo "Expected: '$env_name=$exp_value', but got: '$env_name=$actual_value'"
+      return 1
+    fi
+
+    return 0
+  }
+
+  cd "$SNAP_DIR"
+  SNAPCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS=1 snapcraft
+
+  unsquashfs "${SNAP}"_1.0_*.snap
+
+  # Check that the env-exporter program is present
+  [ -f squashfs-root/bin/command-chain/env-exporter ]
+
+  # Check that the exec-env script is present
+  [ -f squashfs-root/usr/bin/exec-env ]
+
+  snap install "${SNAP}"_1.0_*.snap --dangerous
+
+  echo "[env-injector] Creating global envfile"
+  echo 'HELLO_WORLD="Hello World"' >> /var/snap/"${SNAP}"/common/global.env
+
+  # Load global envfile
+  snap set env-injector-hello envfile=/var/snap/"${SNAP}"/common/global.env
+  echo "[TEST] - Check if the global envfile is loaded for all apps"
+  assert_env "env-injector-hello.hello1" "HELLO_WORLD" "Hello World" || exit 1
+  assert_env "env-injector-hello.hello2" "HELLO_WORLD" "Hello World" || exit 1
+  assert_env "env-injector-hello.hello-demo" "HELLO_WORLD" "Hello World" || exit 1
+
+  echo "[env-injector] Creating app-specific envfile"
+  echo 'SCOPED=Scoped' >> /var/snap/"${SNAP}"/common/appenv.env
+
+  # Load app-specific envfile
+  snap set env-injector-hello apps.hello1.envfile=/var/snap/"${SNAP}"/common/appenv.env
+  echo "[TEST] - Check if the app-specific envfile is loaded for the app"
+  assert_env "env-injector-hello.hello1" "SCOPED" "Scoped" || exit 1
+
+  echo "[env-injector] Setting global env variable"
+  # Set env vars: Global
+  snap set env-injector-hello env.global="World"
+  echo "[TEST] - Check if the global env var is set for all apps"
+  assert_env "env-injector-hello.hello1" "GLOBAL" "World" || exit 1
+  assert_env "env-injector-hello.hello2" "GLOBAL" "World" || exit 1
+  assert_env "env-injector-hello.hello-demo" "GLOBAL" "World" || exit 1
+
+  echo "[env-injector] Setting app-specific env variable"
+  # Set env vars: specific to each app
+  snap set env-injector-hello apps.hello1.env.hello="Hello"
+  snap set env-injector-hello apps.hello2.env.specific="City"
+
+  echo "[TEST] - Check if the app-specific env var IS SET for the app hello1"
+  assert_env "env-injector-hello.hello1" "HELLO" "Hello" || exit 1
+  echo "[TEST] - Check if the app-specific env var IS NOT SET for the app hello2"
+  ! assert_env "env-injector-hello.hello2" "HELLO" "Hello" || exit 1
+
+  echo "[TEST] - Check if the app-specific env var IS SET for the app hello2"
+  assert_env "env-injector-hello.hello2" "SPECIFIC" "City" || exit 1
+  echo "[TEST] - Check if the app-specific env var IS NOT SET for the app hello1"
+  ! assert_env "env-injector-hello.hello1" "SPECIFIC" "City" || exit 1
+
+  snap set env-injector-hello env.word.dot="wrong"
+  echo "[TEST] - Check if the key with dot was ignored"
+  ! assert_env "env-injector-hello.hello1" "" "wrong" || exit 1
+
+  echo "[env-injector] Testing order of env vars"
+  echo 'ORDER="From envfile"' >> /var/snap/"${SNAP}"/common/local.env
+  snap set env-injector-hello apps.hello1.env.order="from app-specific"
+  snap set env-injector-hello apps.hello1.envfile=/var/snap/"${SNAP}"/common/local.env
+  echo "[TEST] - Check if local overrites global"
+  assert_env "env-injector-hello.hello1" "ORDER" "from app-specific" || exit 1
+
+  echo "[env-injector] Run hello-demo app"
+  snap set env-injector-hello apps.myapp.env.specific="City"
+  echo "[TEST] Make sure that alias is NOT rewritten"
+  assert_env "env-injector-hello.hello-demo" "SPECIFIC" "City" || exit 1

tests/spread/extensions/snaps/env-injector-hello/snap/hooks/configure

@@ -0,0 +1 @@
+#!/bin/bash